For buildings of any kind, it is important that they are horizontally aligned. This means that the first layer must already be laid horizontally.

But what if the ground is uneven?

Try to answer the question spontaneously

The height of the first and all other layers is only measured at one corner. The layer height is transferred from this measured corner to the other corners by means of a spirit level or a water level.

Note: never measure the height at different corners.

Note: the bearing joint of the first layer may possibly be of different thickness.

Look at the problem in the info box, please.